A typical aircraft turbofan propulsion system includes a jet engine (also called an engine core, or simply a core), a nacelle that surrounds the engine core, and a fan driven by the engine that draws in a flow of air that is split into a bypass airflow and an engine core airflow. The nacelle defines a bypass duct that surrounds the engine core. The bypass airflow is transported through the bypass duct and exits the bypass duct at a high speed at an aft end thereof. The engine core includes a multi-stage compressor to compress the engine core airflow, a combustor to add thermal energy to the compressed engine core airflow, and a turbine section downstream of the combustor to produce mechanical power from the engine core airflow. The mechanical power from the turbine section drives the compressor and the fan. After exiting the turbine section, the engine core airflow exits through an exhaust nozzle at the aft end of the engine.
Surrounding the engine core is a fire zone in which elevated temperatures must be quickly and reliably detected so that, in appropriate conditions, fire suppression can be employed, or other action taken to ensure the safety of the aircraft.
A fire detection system typically includes one or more thermal detectors, or other types of sensing elements, to provide a warning during engine operation if excess temperatures are detected or other conditions indicative of a fire are detected. The sensing elements are attached to a mounting system, which is attached either to the nacelle, to the engine core itself, and/or to an engine support structure. The sensing elements are suspended away from the surface of the nacelle, the engine core, or the support structure by a mounting system such that the sensing elements detect the conditions in an air space between the engine core and the nacelle.
The spacing of the sensing elements away from the engine core or support structure competes for space also used by other components. In addition to the fire detection system, the space between the engine core and the nacelle is filled with a multitude of components such as valves, tubes, ducts, wires, generators, gearboxes, sensors, etc. In many installations, the space between the engine core and the nacelle is further limited by the need to provide a thermal blanket surrounding all or part of the engine core. The thermal blanket provides thermal and acoustic insulation during engine operation. In many installations, such as nacelles constructed with composite panels, the thermal blanket might be necessary for shielding the composite panel from engine operating temperatures that could damage the composite panel.
A compact and light weight mounting system is desired for mounting the fire detection system in accordance with aircraft regulations and operating requirements, while also ensuring simplicity and accuracy of the installation/assembly and allowing flexibility in the placement of the mounting system components.